By Dr. Mercola
Zinc is an essential trace mineral, probably most widely known for the integral role it plays in your immune system and the prevention and treatment of the common cold. Aside from iron, zinc is the most common mineral found in your body, necessary for the function of every one of your cells.
Zinc is used in the production of white blood cells, helping your body to fight infection, and plays a key role in regulating the way your heart muscle uses calcium to trigger the electrical stimulus responsible for your heartbeat.1
It's also one of the building blocks for approximately 3,000 proteins and 200 enzymes in your body. Recent research has now identified the role zinc plays in protecting your DNA.2
However, while essential, your body does not store zinc, so it is important you get enough from your dietary intake every day. Moreover, regularly getting too much can be just as hazardous as getting too little.
Zinc May Reduce DNA Strand Breaks
DNA is in every cell of your body and is the blueprint your cells use during replication. Until late adulthood your body has the ability to regenerate DNA, but over time DNA does deteriorate, eventually causing the overall breakdown of body systems. Recent research has identified the role zinc may play in slowing this DNA deterioration.
The National Institutes of Health (NIH) has determined a recommended daily amount of identified vitamins, minerals and nutrients that reduces the risk of experiencing symptoms of deficiency. However, a lack of symptoms of insufficiency does not necessarily support optimal health.
The levels recommended for zinc vary with age and gender as the absorption, use and requirements for the mineral varies with those same factors.
Researchers from the University of California San Francisco (UCSF) Benioff Children's Hospital Oakland Research Institute (CHORI) began a study with the intention of measuring the impact small increases in dietary intake of zinc would have on the body's metabolic functions.
Janet King, Ph.D., led the study where 18 men ate a rice-based, low-zinc diet for six weeks. Both before and after the experimental period the researchers measured indicators such as DNA damage, oxidative stress and DNA inflammation.3
When participants increased dietary zinc consumption researchers found a reduction in leukocyte DNA strand breakage, suggesting a modest increase in dietary zinc could reduce the everyday "wear and tear" on DNA. King commented:4
"We were pleasantly surprised to see that just a small increase in dietary zinc can have such a significant impact on how metabolism is carried out throughout the body.
These results present a new strategy for measuring the impact of zinc on health and reinforce the evidence that food-based interventions can improve micronutrient deficiencies worldwide."
While increasing your dietary intake of zinc may be beneficial to your overall health, taking supplemental zinc may not be the way to accomplish your goal.
An Imbalance of Zinc and Copper May Lead to Health Problems
Your body has an elaborate system to maintain balance between trace minerals in your system, such as iron, zinc, copper and chromium. Consuming these minerals in your food helps maintain the proper balance, while taking supplements can easily create an imbalance of too much of one and not enough of another.
Sometimes ingestion occurs knowingly, such as when you take a daily supplement, and other times you may unknowingly absorb more than the recommended daily allowance for a nutrient through another chemical source.
In 2011, researchers from the University of Maryland published a study that demonstrated a hazard of ingesting excess zinc from denture adhesive.5
Excess zinc may lead to a copper deficiency, as the absorption patterns in the gastrointestinal tract are similar. Competition for absorption may lead to an increase in zinc and a reduction in copper.
Too much zinc may lead to nausea, vomiting, stomach cramps, headaches and loss of appetite.6 Getting your zinc from your diet significantly reduces the potential of overdosing.
Copper deficiency can be the result of malabsorption, malnutrition or from an excess of zinc in your system.7 High intake of zinc may increase the creation of metallothionein, a cell protein in your intestines that binds to some metals and prevents absorption.8
These cells have a stronger affinity for copper than zinc. This produces a cycle in which the consumption of zinc triggers the development of metallothionein cells, which then decrease the amount of copper absorbed.
One of the more common symptoms of a copper insufficiency is anemia. In this case the anemia will not respond to an increase in iron, but rather improves with copper supplementation.9
Copper deficiency may also lead to an abnormal low white blood cell count (neutropenia), increasing your potential for infection. In such a case, you may take a zinc supplement to alleviate your cold, for example, thereby worsening your copper deficiency.
Other abnormalities related to copper deficiency include osteoporosis, infants born at low birth weight and loss of pigmentation in your skin.
Zinc Strengthens Your Immune System
Inadequate amount of zinc in your diet may increase your potential for infection. Without zinc, your white blood cells don't function optimally and other processes in your immune system are affected as well. Neutrophils, phagocytosis, antibody production and even gene regulation in your lymphocytes are affected by zinc.10
Although scientists are continuing to study the exact cellular changes an adequate supply of zinc produces on your immune system, some studies indicate it may reduce the duration of your cold by as much as 50 percent, especially if you are deficient.11
Each year there are approximately 200 different viruses that make up the "common cold." While zinc helps support your immune system, it also appears to have antiviral properties that prevent the virus from replicating and attaching to your nasal membranes.12
Researchers have also discovered that zinc may have other immune boosting properties that help your body have a strong first response at the onset of symptoms.13
The initial dose must be taken in the first 24 hours of symptoms to work well, and those taking zinc are less likely have symptoms last more than seven days while supplementing with zinc lozenges.
Adequate Dietary Zinc Intake May Help Prevent Some Diabetes Complications
Some experts estimate that as many as 12 percent of people in the U.S. are deficient in zinc, with as many as 40 percent of the elderly due to poor absorption and low dietary intake.14 Zinc plays a significant role in the reduction of oxidative stress and helping DNA to repair, especially as you age. According to Emily Ho, Ph.D., associate professor with the Linus Pauling Institute at Oregon State University:15
"Zinc deficiencies have been somewhat under the radar because we just don't know that much about mechanisms that control its absorption, role, or even how to test for it in people with any accuracy."
A recent collaborative study with researchers from New Zealand and Australia demonstrated those with zinc blood levels between 14 micromoles and 18 micromoles per liter had the lowest risk of heart disease.17 Optimizing your dietary zinc intake may also improve diabetic markers, such as better glycemic control and lower concentrations of lipids.
Zinc Is Vital to Sensory Organ Function
Taste, smell and vision are three sensory functions in which zinc plays a significant role. Both taste and smell are important to your appetite, so a deficiency may reduce your desire to eat. This can be substantially important in people who suffer from cancer. Zinc deficiency, and the resulting loss of appetite, can be the result of some chemotherapy drugs and radiation treatments used to treat cancer.
In a review of the literature, researchers found a diversity of taste disorders with zinc deficiency.18 Zinc is critical to the production of the metalloenzyme carbonic anhydrase (CA) VI.19 When there is a deficiency of zinc, this enzyme is not made in adequate amounts, leading to loss of taste and, subsequently, appetite.
Your taste and smell systems use CA VI as a growth factor, but it also plays a role in apoptosis, or cell death. If you have a zinc deficiency, apoptosis increases in your body and the cells in your taste and smell organs die abnormally quickly. With an overload of zinc there is another type of alteration that results in further apoptosis and death of those same cells.20
Zinc also works in combination with vitamin A to help your eyes sense light and send the appropriate nerve impulses to the brain for interpretation.21 Your retina, an important part of eyesight, is made of membranes rich in polyunsaturated fats.22 Reactive oxygen species (ROS) may initiate chain reactions of lipid peroxidation that injures the retina, and therefore your eyesight.
Researchers have found a moderate zinc deficiency increases the oxidative stress on the retina and suggest that zinc may be protective against lipid peroxidation of the retinal membranes.23 While oxidative stress on the retina has been demonstrated, the role zinc plays in macular degeneration with age has not been conclusively proven.24 Like other symptoms of zinc deficiency, these appear to be reversible when blood levels return to normal through an appropriate intake of real food.
Improve Your Zinc Intake With Real Food
In this short video, I discuss the importance of zinc to your health, the signs of zinc deficiency and how you may improve your zinc levels through your dietary choices. Vegetarians have a particular challenge as phytic acid in grains compete with the absorption of zinc and other nutrients, which doesn't occur in meat and dairy sources of zinc.
If you have symptoms of a zinc deficiency and choose to use a supplement, ensure it is from a reputable company using best-practice, quality assurance methods. Independent verification of the raw materials is vital to confirm quality and assure it is free of lead and other heavy metals. The supplement should contain several different types of zinc, such as gluconate, citrate and chelate. Unless your clinician recommends otherwise, don't go above 40 milligrams (mg) per day.
Since it's easy to create an imbalance in your body when taking supplements of trace minerals, your most effective way of balancing your zinc levels is through eating real foods high in zinc, such as:25
✓ Pastured beef
✓ Pork chops
✓ Baked beans
✓ Pastured chicken
✓ Pumpkin seeds
✓ Swiss cheese
✓ Kidney beans
✓ Cheddar cheese